1. Field of the Invention
The invention in general relates to the field of chemical analysis, and particularly to apparatus which concentrates a liquid sample so that it may easily be chemically analyzed for detection of impurities.
2. Description of the Prior Art
The need for the precise monitoring of high purity liquids exists in many industries. Very low levels of impurities in the liquid can be extremely detrimental in the manufacture of, for example, semiconductors, pharmaceuticals, and in the power generation field, to name a few.
For example, in a steam turbine generator power plant, ultrahigh purity water is utilized in the generation of the steam which drives the turbines. The corrosive effects of impurities on turbines, boilers and other critical components in steam turbine power plants are well known and for this reason the circulating water for steam generation is maintained at an ultrahigh purity level measured in parts per billion, resulting in decreased outages and lower maintenance costs.
As part of the program for maintaining a high purity level of the water, it is necessary to collect representative samples of water or steam condensate from various locations in the steam turbine system so that they may be analyzed in order that corrective measures, if required, may be made.
Equipment exists for chemically analyzing the fluid utilized in various industrial processes, however, a problem exists in some plants, such as a steam turbine generator power plant, in that measurements must be made involving impurities measurable in parts per billion and even in parts per trillion. Direct constant monitoring of impurities at such low levels is extremely difficult and many commercial analyzers are not reliable to make measurements of impurity concentrations in this low range. To alleviate the problem, many processes use some sort of a concentrator to concentrate the sample provided for analysis.
A concentrator utilized in the monitoring of industrial process fluids, such as power plant water chemistry, should have high reliability and should be able to provide an output on a continuous flow basis with a reproducible concentration ratio of all chemical species of interest. Lower detection limits and increased sensitivity have been achieved through use of batchwise concentration techniques such as evaporation, liquid-liquid extraction, column ion exchange and reverse osmosis, however, these techniques either cannot be used with a continuous flow analyzer or are generally slow and laborious.
The present invention overcomes the deficiencies of the prior art apparatus and has the above-enumerated desired characteristics.